Troops engaging at Antietam

Maryland Historical Society

The bloodiest single-day battle of the American Civil War took place at Sharpsburg, in Washington County, Maryland, on Wednesday, September 17, 1862. It marked the end of the first invasion of the North by Confederate Gen. Robert E. Lee's Army of Northern Virginia (40,000) which was calculated to influence forthcoming northern midterm elections and precipitate intervention in the war by Great Britain and France. Southerners hoped to force the North to sue for peace, thereby granting southern independence. The battle ended in a tactical draw, and the Confederacy did not attain either of its objectives.

Antietam was the first battle fought on northern soil. It led to President Abraham Lincoln's issuance of a preliminary Emancipation Proclamation just five days afterward that expanded northern war aims to include the abolition of slavery in addition to preservation of the Union. Thereafter the South was forced to defend itself against the North's greater industrial resources without international assistance.

Casualties at Antietam numbered more than 23,000 men killed, wounded, and missing in a single day, nine times the number of American casualties suffered in the D-Day landings at Normandy in World War II. More American soldiers were killed and wounded at the Battle of Antietam than in the Revolutionary War, the War of 1812, the Mexican War, and the Spanish-American War, combined.

Prologue
Following a rearguard action on September 14 at the Battle of South Mountain (Turner's Gap and Fox's Gap), but still seriously threatened by a Union strategic breakthrough farther south at Crampton's Gap, Lee moved overnight to Sharpsburg to consolidate his widely divided forces. He was joined there by Gen. Thomas J. "Stonewall" Jackson's command after Jackson's successful siege and capture of the Union garrison at Harpers Ferry. Union Gen. George B. McClellan's Army of the Potomac (87,000) pursued Lee to the banks of Antietam Creek but delayed attacking until the September 17 to give Federal forces time to assemble. When McClellan began his assault, Union troops crossed the creek by three stone bridges in three uncoordinated phases:

Dawn to 9:30 a.m.
McClellan opened the battle by way of the Upper Bridge. Gen. Joseph Hooker's First Corps attacked Lee's left flank in an attempt to turn it, which would allow access to Lee's rear echelon. Massed Union troops moved from the North Woods south down the Hagerstown Pike. Jackson's Confederate command held the West Woods from which attacks were repeatedly repelled near the Dunker Church, Hooker's objective at the West Woods' eastern edge.

Midway between North, East, and West Woods was the thirty-acre cornfield of farmer David Miller, the only available shelter for troops moving between them. The Cornfield changed hands many times in savage charges and counterattacks that left "every stalk of corn.cut as closely as could have been done with a knife, and the slain lay in rows," Hooker recorded.

Unable to make headway, First Corps gave place to Gen. John Mansfield's Twelfth Corps attacking westward from the East Woods. This too was blunted by counterattacking brigades of Gen. James Longstreet's Confederate command. A division of Gen. Edwin V. Sumner's Second Corps managed to penetrate the West Woods near the Dunker Church but was outflanked and driven back. In this horrendous first phase of battle over 12,000 men were shot down in the span of three and a half hours, one American for every second of fighting.

Lithograph closeup of the battle

Maryland Historical Society

9 a.m. to 11:30 a.m.
Part of the Second Corps then launched a frontal attack on Lee's center, commanded by Confederate Gen. Daniel H. Hill. This section of the Confederate line was concealed in and protected by an eroded farm road fronting the William Roulette Farm. Hill's men stubbornly clung to their positions and inflicted heavy losses as each Union battle line came into view. Federal brigades were turned back with ease. So withering was the Confederate fire that a single volley dropped every man in the lead rank of one Union regiment.

Union troops finally fought their way to a position on Hill's right flank and fired down the lane. What was once a strong position instantly became a death trap, grotesquely piled with Confederate dead and wounded and ever after known as "Bloody Lane." Hill's soldiers hurriedly withdrew to the Henry Piper farm in their rear to make a stand, but they had so punished Second Corps that no further advance was made against them.

Around midday Gen. Alfred Pleasonton's Union cavalry and portions of Gen. Fitz-John Porter's Fifth Corps were pushed over the Middle Bridge westward toward Sharpsburg, but did not become generally engaged.

Noon to Dusk
The third and final phase of the battle unfolded as a prolonged push against Lee's right wing south of Sharpsburg focused on the Lower Bridge over Antietam Creek. Union Ninth Corps commander Gen. Ambrose P. Burnside was ordered to cross the Lower Bridge and ascend the heights below the town. After several attacks on the bridge were broken up by a handful of Confederates, one of Burnside's divisions found a downstream ford and outflanked the heavily outnumbered defenders.

Meanwhile the main body of the Ninth Corps troops forced its way over the bridge and fought uphill onto the open farmland. Burnside's skirmishers penetrated Sharpsburg streets as Confederate defenders, hurriedly sent in from other sectors, rapidly gave ground. Lee appeared to be in serious trouble. If his right flank broke he would lose his sole road of escape to the Potomac River.

At the last minute, Gen. Ambrose P. Hill's division arrived. They were the last Confederate troops to leave Harpers Ferry but after an exhausting march they struck Burnside's flank with great ferocity and drove Burnside's regiments back to their bridgehead for the night. The bridge is now known as "Burnside's Bridge."

Troops on the field of Antietam

Maryland Historical Society

Twilight put a merciful end to hostilities. Lee's army had barely survived the day. His left flank was drained and his center had been driven in, but his right wing was stable for the time being.

On Thursday, September 18, McClellan chose not to renew his attacks. Both armies had been badly mauled and declared a truce to collect the vast numbers of wounded. Lacking the strength to drive off McClellan, Lee abandoned the battlefield on the night of September 19 and re-crossed the Potomac into Virginia. The next day a sharp engagement with the Confederate rearguard at Shepherdstown Ford halted Union pursuit. Thus ended the campaign.

Lee marched north again in 1863, but by then northern voters had ratified Lincoln's war policies and foreign powers had decided not to intervene in American affairs. After Gettysburg, Lee would remain on the defensive until war's close.

Harsh, Joseph L. Taken at the Flood: Robert E. Lee and Confederate Strategy in the Maryland Campaign of 1862. Kent, Ohio: The Kent State University Press, 1999.

Murfin, James V. The Gleam of Bayonets: The Battle of Antietam and the Maryland Campaign of 1862. Baton Rouge: Louisiana State University Press, 1965.

Sears, Stephen W. Landscape Turned Red: The Battle of Antietam. New Haven: Ticknor & Fields, 1983.